1. Field of Invention
This invention relates to an improved smoke-producing composition for use by the military to produce a screening cover for field operations.
More particularly, this invention relates to a smoke-producing composition for battlefield screening whose initiation is rapid and whose smoke-cloud is effective in volume and efficient in persistence and duration as a military screen.
2. Description of Prior Art
Red phosphorus, the comparatively inert allotropic form of phosphorus, is used in burning-type munitions mainly for signaling purposes. Compositions consisting of red phosphorus are generally used as sea-markers. However, there is a need for smoke producing munitions for battlefield screening that will develop a large dense cloud quickly and which will sustain the cloud for a relatively long duration. Rapid ignition, large volume of smoke, long duration, and persistency or visibility are all required for military screening operations. None of the compositions of the art have or exhibit all of the latter requirements. The most suitable red phosphorus composition for military use takes 2.5 minutes to develop a cloud, and the cloud produced persisted for only 3.5 minutes in duration which limits its military use to signaling.
Standard compositions and those which use red phosphorus are incapable of meeting performance requirements due to their unfavorable ignition period and their fast burning rate. The requirements for military screening operations are difficult to accomplish since the smoke composition must develop a large volume of smoke rapidly, and yet continue to burn at a very slow rate for a long duration producing a persistent cloud of smoke which is visible for a relatively long period of time.
Red phosphorus compositions of the art have a burning time of 210 seconds, however a burning time of 600 seconds is required. In addition, the red phosphorus compositions known to date produce very toxic and mutagenic reaction products from their mixed compositions. The latter mainly precludes their use in screening operation. Further, the red phosphorus compositions of the art are very slow to ignite, and can be readily extinguished particularly during the early burning phase by adverse climatic conditions.
What is needed in the art is an improved smoke-producing composition which will produce a cloud relatively rapidly and yet will burn for a long period of time thereby producing a cloud which persists for a sustained duration when compared to compositions of the art.